1. Technical Field
The present invention relates to a method and system for servicing a wireless communication network in general, and in particular to a method and system for servicing a mobile telephone communication network. Still more particularly, the present invention relates to a method and system for handling a call from a mobile station within a mobile telephone communication network.
2. Description of the Prior Art
Today, wireless telecommunications represents a large and continuously increasing percentage of all new telephone subscriptions around the world. The specifications for a Global System for Mobile Communication (GSM) digital mobile cellular radio system was formulated by a standardization group known as European Telecommunications Standards Institute (ETSI) established in 1982.
A typical cellular mobile telecommunication system includes multiple geographic regions known as cells. Each cell contains at least one base transceiver station (BTS). A BTS communicates directly with a mobile station (or mobile telephone) located in a corresponding cell. Several cells are grouped within a location area that contains one or more mobile switching centers (MSCs), and each of the MSCs is typically connected to several BTSs within the location area. The primary function of an is to execute the switching requirements necessary to properly route calls between a mobile station located in one cell and a mobile station located in another cell. In addition, an MSC may be connected to a public switching telephone network (PSTN) such that the MSC can also facilitate the routing of calls between a mobile station and a fixed telephone terminal connected to the PSTN.
A home location register (HLR) can be associated with one or more MSCs. An HLR, which is essentially a database, maintains a user record for each of a number of mobile stations associated with a corresponding service area, and these mobile stations are said to be assigned to the HLR. Each record within an HLR contains, among other things, an identification code for the corresponding mobile station, information regarding the type of service associated with that mobile station, and information defining the current location of the mobile station. Another component that is used in providing a mobile station with the capability to transmit and receive calls while roaming is a visiting location register (VLR). A VLR, which is also a database, is typically associated with a corresponding MSC. Unlike an HLR, a VLR maintains a user record for each visiting mobile station. When a mobile station roams into a location area, a record identifying that mobile station will be established in a VLR. When the mobile station leaves the location area, the record identifying that mobile station is deleted from the VLR.
In addition to basic cellular service, many cellular mobile telecommunication systems also provide intelligent network (IN) services. IN services may include, for example, the ability to place originating IN calls such as placing a call to a fixed telephone terminal by dialing only a four digit extension rather than the entire seven or ten digit telephone number. Those skilled the art will recognize that such IN service is often referred to as a private numbering plan. A component known as a service control point (SCP) is typically required to provide IN services. More particularly, the SCP maintains the service logic and instructs the corresponding MSC to perform action, such as playing tones and announcement, in order to provide the service to a mobile subscriber.
The disadvantage of the current SCP implementation is that the SCP is not aware of the capabilities of the mobile station with which a mobile subscriber uses to answer an incoming call, and transmissions of error messages from the MSC to the SCP are required to be invoked as a result. Specifically, when a mobile subscriber answers an incoming call with a mobile station, an associated SCP may send a message to a corresponding MSC directing the MSC to provide certain functionality. Upon receiving the message from the SCP, the MSC may then realize that the mobile station does not have the capability to support the requested functionality. At this point, the MSC sends an error message back to the SCP, indicating that the requested functionality cannot be provided. The error message typically includes a cause parameter for indicating the cause of failure. In this case, the cause of failure would be the lack of capability of the mobile station to provide the requested functionality originated by the SCP.
For example, according to the GSM IN standard, there is a function called Send Charging Information (SCI). An SCP can invoke this function by sending an SCI message to an MSC when the MSC has indicated to the SCP that a subscriber with intelligent network services has originated a call. The SCI message contains parameters, which when sent to the mobile station, to indicate to a mobile subscriber the current credit balance available. The SCI message can also indicate the running cost of the call that the mobile subscriber is currently on. However, this function can only be provided by mobile station that has Phase 2 capabilities. Thus, when the MSC receives an SCI message from the SCP, the MSC needs to determine whether or not a receiving mobile station has the Phase 2 capabilities. If the receiving mobile station does have Phase 2 capabilities, the call proceeds as normal and the parameters will be sent to the receiving mobile station. Otherwise, if the mobile station does not have phase 2 capabilities, the MSC will then send an error message back to the SCP with a cause parameter indicating the cause of failure.
The present disclosure provides an improvement to the current SCP implementation such that transmissions of error messages from the MSC to the SCP can be reduced.
In accordance with a preferred embodiment of the present invention, a mobile telephone communication network includes a mobile switching center (MSC) and a service control point (SCP). After a call has been initiated from a first mobile station to a second mobile station, the MSC sends an initialDP message to the SCP. The initialDP message preferably includes a classmark field. In response to the call from the first mobile station to the second mobile station, the MSC sets up the call to the second mobile station. The MSC then notifies the SCP that the call to the second mobile station has been initiated. Finally, the MSC receives a request from the SCP to inform the SCP when the call being answered by the second mobile station.
All objects, features, and advantages of the present invention will become apparent in the following detailed written description.